Ball-point pen



J. A. SALAS BALL-POINfl PEN July 5, 1949.

Filed May 2, 1947 INVENTOR. Jose Amoma Salas v H 7"TORNE Y Patented July5, 1949 UNITED STATES PATENT "OFFICE BALL-POINT PEN Jos Antonio Salas,Caracas, Venezuela Application May 2, 1947, Serial No. 745,590

4 Claims. i

This invention relates in general to writing pens and in particular topens having a ball point and includes correlated means designed toenhance the utility and to facilitate the useful life of such pens.

In general, ball pens are characterized by employing a relativelyviscous ink as compared with the ink used in other types of writingpens. Such ink is characterized by flowing with difiiculty under gravityso that frequently the flow of ink to the ball stops even though the inkis not exhausted. Various means have been proposed to overcome thisdisadvantage but the means heretofore proposed have not beensatisfactory.

One prior means has been a piston which was threaded into the upper endof the ink-containing cylinder. By applying pressure on the piston, theink was caused to flow more readily. It is characteristic of liquids,however, that they cannot be compressed. Therefore, if by chance thesmall capillary channel leading to the ball point should become clogged,the pressure applied by such a piston will frequently cause the inkchamber to burst. It is well recognized that by a simple threaded screw,pressures of several thousand pounds per square inch can be obtained insuch a hydraulic system.

The present invention has for its general object the provision of meansfor overcoming the disadvantages above mentioned in ball point pens.

A specific object of the invention is to provide a ball point writingpen with means to apply a yielding pressure on the ink in the pen tofacilitate its proper flow to the ball.

It is a further object of the invention to provide a ball point writingpen having means to enable the user to test the level of the ink in thebarrel.

It is a further object of the invention to provide a ball point writingpen having means to prevent the ink from leaking out when the pen isturned upside down.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

According to the present invention, there is provided a ball pointwriting pen having, in combination, an elongate ink container, a writinghead incorporating a ball point closing one end of said container, apiston closing the upper end of said container, said piston having avent therein communicating with a closed air chamber. When pressure isapplied on the piston to compress the ink, the ink will rise through thevent tube and compress the air in the air chamchamber gives a measure ofthe amount of ink remaining unused.

For a more complete understanding of the nature and objects of theinvention, reference should be had to the accompanying drawing in whichi Fig. 1 is a side elevation, partly in section, of one embodiment ofthe pen of the invention;

Fig. 2 is a cross-section of the pen of Fig. 1 taken along the line 2-2thereof;

Fig. 3 is a fragmentary view, in side elevation and in section, of asecond embodiment of the D Fig. 4 is a fragmentary view, in sideelevation and in section,.of a third embodiment of the pen; and

Fig. 5 is a fragmentary view, in side elevation and in section, of afourth embodiment of the pen.

The essential principle of*the present invention is the fact. thatthe'pen comprises an elongate ink chamber adapted to hold ink and amemberarranged and positioned to be reciprocated in the ink chamber andcover the upper surface'of the ink.

The piston has an aperture or channel communicating with a closed sealedair chamber. Preferably the communicating channel is an elongatecapillary tube open at both ends. The upper end communicating with theclosed air chamber or the capillary may be bent into a U- shape with thelower end of one arm closed.

By way of illustration but not by way of limiting the invention, severalspecific embodiments will now be described.

Referring to Fig. 1, the pen comprises a writing head [0, havin aconventional socket l I at the lower end adapted to enclose a ball [2with suflicient clearance to allow the ball to rotate therein andprovided with an ink channel l3, the lower end of which communicateswith the socket H and the top end communicates with a socket I l adaptedto support therein an elongate container I5 adapted to contain thewriting ink It. The head I0 is provided at its upper end with a threadedarea 2| adapted to engage the lower threaded end 22 of the barrel 23.The barrel is 3 hollow through the major portion of its length and thusencloses the ink container l5.

In this embodiment the piston 16 conforms to the shape of the interiorof the container and fits tightly therein and slidably engages thewalls. The piston is preferably a block of material having one or morerings H of rubber embedded in the surface and contacting the walls ofthe container l5 and serving to make an air-tight and liquid-tight seal.It is essential that the piston fit very tightly. In the embodimentshown in Fig. 1, there is provided above the piston a sealed air spaceby means of an inverted cylinder ll threaded at its lower end to theupper end of the piston and having its upper end I9 closed. The pistonis provided with an elongate hole into which is threaded a capillarytub? 24 open at both ends, the upper end being adjacent the closed endIQ of the tube l8.

In use, the pen shown in Fig. 1 is filled with ink and the pistoninserted initially in the position shown. Whenever it is desired toapply pressure tothe ink, the barrel 23 is removed and pressure isapplied on the piston by pressing downward on the tube 18. When the inkis thus brought under pressure, a small amount of ink will rise in thecapillary tube 20 and compress the air in the closed container l8, thusrelieving the pressure on the ink. As the ink is gradually used up, thepiston is pressed further and further into the lower container IS. Theheight of the piston will indicate the level of the ink.

That embodiment shown in Fig. 3 is similar to that shown in Fig. '1except that the capillary tube is bent into an inverted U. One leg, ofthe tube 24a is enlarged and sealed to provide the closed air chamber 25while the other leg is open and passes through an aperture in the pistonIlia. When pressure is applied on the ink by pressing the piston liq.downward, the ink will tend to rise in the capillary and compress theair in tube 24a and bulb 25.

at mbodiment shown in Fig. 4-is also similar in construction to thatshown in Fig. 1 except that the air tube I811. is fixed to the barrel23o by means of the projection 26- which is threaded into the upper end21 of the barrel 23a. In this embodiment the barrel 23a is not threadedto the lower container Iiiv but is ground to fit smoothly on and slideover the lower body of the pen as shown in the lower part of Fig. 4. Toapply pressure to the piston, the barrel 23a is merely pressed downwardtoward the writing head. This tends to' shorten the pen but also gives ameasure of the ink supply remaining. As in the other embodiments, thepressure thus applied will be relieved by the ink compressing the air inthe closed chamber [8a.

That embodiment shown in Fig. 5 issimilar in tial portion of its outersurface, such threads 33 engaging the threads 32-. In operation, whenthe upper part of the barrel 230 is rotated, this will cause thethreaded air chamber lBc to be moved downward, thus applying pressurethrough the piston I6 against the ink in the container I5, the pressurebeing relieved in the same manner asin the embodiment shown in Fig. 1.

I claim:

1. In a ball-point writing pen, the combinationof an elongate inkcontainer, a writing head incorporating a ball point closing one end ofsaid container. a piston closing the upper end of said container, aclosed air chamber, and a vent in said piston communicating with saidair chamber, whereby a yielding, pressure is applied to the ink in saidcontainer when pressure is applied to said piston.

2. A ball-point writing pen as claimed in claim 1, in which said airchamber comprises an inverted U-tube having one closed end and the otherend communicating with said ink chamber.

3. A ball-point writing pen as claimed in claim 1, in which said airchamber comprises a cylinder having an upper closed end and the otherend fixed to said piston, and said vent comprises a capillary tubepassing through said piston and terminating adjacent the closed end ofsaid cylindert 4. A ball-point writing pen as claimed in claim 1, inwhich said ink container and said air chamher are coaxial cylinders, oneof said members containing threads on the inner surface and the othercontaining corresponding threads on the outer surface to permit one ofsaid members to be screwed inside the other.

JOSE ANTONIO sALAs.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number- Name Date 498,213 Miller Ma 23, 1893873,769 Morris Dec. 17, 1907 FOREIGN PATENTS Number Country Date 476,971Great Britain 1937

